British comedian Simon Brodkin, who uses the stage name Lee Nelson, handed a P45 letter, a document given to employees when they leave their job, to Theresa May as she gave her speech

Theresa May addresses the Conservative Party conference in Manchester (Reuters)

MANCHESTER, England: British Prime Minister Theresa May's bid to reassert her dwindling authority was marred on Wednesday by a calamitous keynote speech interrupted by repeated coughing fits, a prankster and even letters of her slogan falling off the stage.

May had wanted to use the Conservative Party's annual conference to bring her divided party together and pitch herself as the only person able to deliver Brexit and keep opposition Labour leader Jeremy Corbyn out of power.

She started by apologising for her botched bet on a snap June election which stripped her party of its majority in parliament, then pitched a revitalised "British Dream" for which she proposed fixing broken markets and uniting the country.

But her flow was interrupted by British comedian Simon Brodkin, who handed her a P45 letter, a document given to employees when they leave their job. The document had been "signed" by the comedian using the name of her ambitious Foreign Secretary Boris Johnson.

Then May began a coughing fit and was repeatedly forced to take drinks of water, even coughing into her glass, and was proffered a lozenge from her finance minister, Philip Hammond.

While she was speaking, several letters fell off the slogans behind her on the stage. Some Twitter users seized on images of the missing letters to poke fun at the Conservatives: one said their glue was even failing to hold the party together.

The 61-year-old May won standing ovations for pressing on with the hour-long address, in which she took a more personal tone - saying she did not mind being called the "Ice Maiden" and describing her "great sadness" at not having children.

Her speech sought to offer party activists a renewal of Conservative values while making new promises to a younger generation and those "just about managing".

"This is a Conservatism I believe in, a Conservatism of fairness and justice and opportunity for all, a Conservatism that keeps the British dream alive for a new generation," she told the cheering crowd.

"That's what I'm in this for," she said, in a phrase she repeated at least eight times. "That's what we must all be in this for."

May, who was warmly embraced by her husband on stage after she had finished speaking, later poked fun at her coughing fit by tweeting an image of cough lozenges and medicine laid beside a paper copy of the address and her prime ministerial briefcase.

Brexit minister David Davis told Reuters it had been "a very good speech, it hit all the issues people care about". Other cabinet ministers also applauded May.

Theresa May had said UK would continue to "honour its commitments" under the EU's current budget

Many in the audience said her coughing fit and the sudden appearance by the comedian had helped to win them over.

"Actually, if all that stuff hadn't happened, it would have just been another kind of wooden presentation," said Pippa Smith, a 26-year-old party member from London. "It was a good speech, but I think actually it did her a favour."

Opponents were less kind.

Nigel Farage, the former leader of the United Kingdom Independence Party, said May was so useless that if she remained as leader then Labour's Corbyn would soon be in power.

Labour lawmaker Seema Malhotra said: "It just couldn't get worse than this. What a disaster. It's a shambles, not a government."

But there are few obvious successors yet visible besides Johnson, who is unpopular with some Conservative lawmakers. Some activists fear that a divisive leadership contest would pave the way for an election that Corbyn's Labour could win.

MAY DIMINISHED

The conference in the northern English city of Manchester was a sombre affair, light on policy and heavy on self-doubt. Despite coming second in the June election, the opposition Labour Party's annual meeting a week earlier was celebratory.

After Labour's assault on some elements of capitalism, the backbone of Conservative policy, May sought to make the case for free markets and fiscal prudence.

"The free market - and the values of freedom, equality, rights, responsibilities, and the rule of law that lie at its heart - remains the greatest agent of collective human progress ever created," she told members.

"Because there has rarely been a time when the choice of futures for Britain is so stark. The difference between the parties is so clear."

She tried to compete with Labour on its pledges to voters, offering 2 billion pounds to build cheaper houses, proposing a cap on what she called "rip-off" energy prices and to ease the burden of student debt.

Labour leader Corbyn said May had simply taken a few Labour policies and watered them down.

Business leaders reacted warily to May's plan for more government intervention in power and housing markets, and said big unanswered questions about Brexit would drag on the economy.

But most party members said that, rather than policy, they wanted to see a return of May's confidence, crushed in the June election, when she earned the nickname "Maybot" for repeating catchphrases.

"We did not get the victory we wanted because our national campaign fell short," she told members. "I hold my hands up for that. I take responsibility. I led the campaign. And I am sorry."

But she also told her party to unite, as divisions over Brexit have come to the fore with a challenge by her foreign minister, Boris Johnson.

The run-up to May's speech was again overshadowed by Johnson, who once more dominated the airwaves after stunning some party members at the conference by saying Libya could become a new Dubai if it could "clear the dead bodies away".

"Let us shape up and give the country the government it needs," May said.

"For, beyond this hall, beyond the gossip pages of the newspapers, and beyond the streets, corridors and meeting rooms of Westminster, life continues - the daily lives of ordinary working people go on. And they must be our focus today."